Fabrication And Electrical Properties Of Lead Free Piezoelectric Ceramics With High Strain Response

Over the past half century, PZT-based piezoelectric materials have dominated the application areas of actuator, transducer and sensor due to their excellent electromechanical properties. However, there is a high toxic lead content in this kind of material which can trigger great damages to human bodies and environment. As a result, developing friendly lead-free piezoelectric materials has been becoming a hot research direction in recent years.(1-x)Bi0.5Na0.5Ti O3-x Ba Ti O3(BNT-BT, BNT-x BT) based ceramics have the good piezoelectric property with the composition around morphotropic phase boundary(MPB). Based on this principal, it has attracted much research attentions to develop the novel lead-free piezoelectric materials with high electric-induced strain.According to first-principle calculation, theoretically Bi(Zn0.5Ti0.5)O3(BZT) and Zn Sn O3(ZS) systems are promising lead-free candidate and own excellent ferroelectric performance. However, it is extremely hard to synthesis them through the conventional synthesis methods. In order to take advantage of their good electric properties, in present work we aimed to introduce them into lead-free Bi0.5Na0.5Ti O3-Ba Ti O3(BNT-BT) and Ba Ti O3(BT) piezoelectric system, and subsequently obtained pure ternary BNT-BT-BZT(BNT-BT-x BZT) and binary BT-ZS(BT-x ZS) solid solutions. The main results are as follows:The introduction of BZT induced structure transformation from ferroelectric tetragonal phase to pseudocubic rhombohedral phase near room temperature in the BNT-BT-BZT ceramics, which was accompanied with a giant strain. A large strain of 0.23%(Smax/Emax=526 pm/V) at a low driving field ranging from 4 k V/mm was obtained at a critical composition x of 0.05 at room temperature, which is superior to those of the reported lead-free BNT-based piezoelectric ceramics. The strain show good temperature stability in the temperature range of 25 oC to 120 oC. In addition, it was worth noting that the BNT-BT-BZT ceramics also presented an excellent fatigue-free response. All these demonstrated that this lead-free piezoelectric solid solution has potential application in actuators.All the BT-ZS ceramics with the composition x of 0-0.10 exhibited pure perovskite structure. The phase transformation from ferroelectric tetragonal to cube phases was induced with the increasing of ZS, which should be responsible for the giant electrostrictive coefficient. At x of 10% mol, a strong electrostrictive effect was observed under an electric field of 4 k V/mm at room temperature, which is even superior to the well-known electrostrictive material Pb(Mg1/3Nb2/3)O3. Furthermore, the electrostrictive response exhibited good temperature stability in the temperature range of 25 oC to 120 oC, which is also quite favorable for practical applications.